The distributor for an internal combustion sequentially distributes high tension voltage to spark plugs for igniting the air-fuel mixture in combustion chambers under optimum compression conditions. The efficiency of the engine and the quality of the exhaust requires that the distributor provide the spark producing voltage in each combustion chamber at the correct time. Improper timing will cause, among other things, significant decrease in engine efficiency and a corresponding increase in exhaust pollutants.
To provide the spark producing voltage at the proper time, the distributor includes a cam, a movable arm with a rubbing block or cam follower, and a pair of contact points. One of the points is secured to the movable arm and the points are normally urged closed by a spring connected to the arm.
The cam is rotated by the engine through gears, and includes a number of lobes with high points which correspond to the number of combustion chambers. As the cam is rotated the lobes sequentially are positioned adjacent the cam follower. For a predetermined number of degrees of rotation of each lobe, the points remain closed because the cam follower is not in contact with the high point on the adjacent lobe. When the points are closed, current at a relatively low voltage from the ignition system passes through the points. During this time spark producing voltage is not provided to the spark plugs.
As each lobe continues to rotate its high point moves toward and comes into contact with the cam follower. At this time the cam opens the contact points. The desired distance between opened contact points always is reached at the high point of each cam lobe. When the points are opened a high tension voltage is introduced in the system which passes through the distributor to a designated spark plug for igniting the airfuel mixture in the combustion chamber.
The number of degrees of rotation of the cam during which the points are closed is called cam or dwell angle. The optimum distance between the points effected by a cam lobe is called the contact point gap or setting. This setting, generally determined by the manufacturer of the engine, contributes to the amount and time of the spark inducing voltage at a plug which the manufacturer believes is necessary for proper running of the engine.
The contact point gap or dwell angle must be set accurately. If the dwell time is too short a weak spark will result at the plug. If the dwell time is too great, the contact points will not open long enough resulting in a loss of timing and misfiring in the combustion chamber.
Moreover, as the points are opened a condensor or capacitor electrically connected to the movable point provides a place for current to flow while the contact points are open. Without a condensor, or with a defective one, arcing will occur which will seriously limit the useful life of the points.
To meet exacting conditions, and because of mechanical and electrical wear, the contact points and to a more limited extent, the condensor and related equipment should be replaced periodically.
Prior to the present invention, each change of distributor components, particularly the points and condensor, has been relatively complex and expensive. Each time special tools and equipment must be used to provide an accurate gap setting and dwell angle. Frequently, each component each time also requires separate disconnection and removal, and subsequent replacement and electrical connection. Due to complexities, the maintaining and service procedures are time consuming and more often are done by a mechanic who must have expertise. Also the service costs are meaningful and the services provided at the inconvenience of the vehicle owner.
Moreover, prior to the present invention, the spring means connected to the arm which normally urged the points closed, only applied pressure and did not provide point alignment. As a result the points commonly were misaligned causing inefficient electrical transfer between the points and excessive wear.
Thus, prior to the present invention, contact point and condensor devices and systems have been beset by a number of significant drawbacks.